We measure the width of the wrinkled zone [1]}, [2]} by identifying peaks in the second derivative of the amplitude profile (Fig. REF b), and plot this \(r_{\text{wr}}\)  as a function of \(\eta \)  in Fig. REF a (left panels). Chopin et al. predicted that for a ribbon of finite thickness, \(r_{\text{wr}} = 0\)  until the critical \(\eta _{\text{lon}}\)  after which \(r_{\text{wr}}\)  might jump directly to the NT curve ([1]}, Eq. (3)),
\(\left(1 - 12 r_\text{wr}^2\right) = \frac{24}{\alpha },\) 
